Excavating tool

ABSTRACT

An excavating tool, especially for forming holes in earth formations for receiving pipes, and in which the excavating tool includes, at the working end, a tiltable member so that, after a pipe receiving hole is formed, a pipe can be introduced into the hole and through the opening provided by the tiltable portion on the bit thereby permitting the bit to be retrieved.

[451 Dec. 9, 1975 2/1965 Chauvin.......................... 6/1968Kozar....... 3/1972 Kniff.... 5/1973Benetti..................................

ABSTRACT 9 Claims, 4 Drawing Figures Prima ry Examiner-Frank L. AbbottAssistant Examiner-Richard E. Favreau Attorney, Agent, or FirmMelvin A.Crosby An excavating tool, especially for forming holes in earthformations for receiving pipes, and in which the excavating toolincludes, at the working end, a tiltable member so that, after a pipereceiving hole is formed, a pipe can be introduced into the hole andthrough the opening provided by the tiltable portion on the bit therebypermitting the bit to be retrieved.

XX Mm MM 57 .ll 1

EXCAVATING TOOL Michael A. College, Everett, Pa.

June 12, 1974 Appl. N01: 478,503

1757 2 isIE 7Q, 404, 382,

References Cited UNITED STATES PATENTS 1/1963 Adams et 6/1963Gruere..........; 6/1964 Robinsky........................

United States Patent College [75] Inventor:

[73] Assignee: Kennametal Inc., Latrobe, Pa.

[22] Filed:

[52] US. [51] Int.

[58] Field of Search Sheet 2 0f 2 3,924,697

US. Patent Dec. 9, 1975 EXCAVATING TOOL The present invention relates toexcavating tools and is particularly concerned with a bit arrangementespecially adapted for use in connection with an excavating tool forforming holes in earth formations and the like for receiving pipes.

The forming of holes in earth formations for receiving pipes is a wellknown work procedure that is generally carried out by utilizing atubular drill string having a bit on the outer end. The bit and drillstring are rotated and advanced into the formation and a hole is therebyformed in the formation.

Usually, the bit is not retrievable but is, instead, disengaged from thedrill string by rotating the drill string in the reverse direction. Thebit in such a case is left in the hole and the pipe is inserted,usually, through the drill string before the drill string is retractedfrom the hole.

The act of leaving a bit in the hole each time represents considerableexpense, and it is proposed by the present invention to construct a bitfor the aforesaid purpose which will permit a pipe to be introduceddirectly through the bit into the hole whereby retraction of the drillstring from the hole will also recover the bit so that the bit can beused again.

BRIEF SUMMARY OF THE INVENTION According to the present invention, a bitstructure is provided adapted for being threaded on the end of a drillstring, or for being welded or otherwise affixed to the end of a drillstring or to a short piece of drill pipe. The bit is provided withcutters mounted thereon which determine the size of the hole to beformed. The cutters protrude radially outwardly slightly from theenvelope of the drill pipe and, thus, permit the drill pipe to followreadily into the hole being formed as the bits reduce the formation.

The residue taken by the bit can be flushed rearwardly along the outsideof the drill string so that the bit and drill string can proceed intothe formation. According to the present invention, the bit comprises acentral hole through which flushing liquid, water, for example, can passto the bit and through which a pipe to be introduced into the formedhole can be fed after the hole is completely formed.

The bit includes a bar portion extending transversely across the centralopening or hole in the bit structure and which bar portion is pivotallyconnected to the outer part of the bit structure at one end of the barportion. The bar portion includes at least a centrally disposed pilotcutter and may include other cutters radially outwardly from the pilotcutter.

Due to the tiltable bar overlying the central opening in the bit, thepipe to be placed into the hole that is formed by the bit and drillstring can be introduced through the drill string and the centralopening in the bit structure by outward tilting of the aforementionedbar and whereupon the drill string, together with the bit, is withdrawnfrom the hole thereby recovering the bit for further use.

The exact nature of the present invention will become more apparent uponreference to the following specification taken in connection with theaccompanying drawings in which:

FIG. 1 is a side view of one form which the invention can take.

2 FIG. 2 is a plan view of the FIG. 1 modification with thecircumferential cutters shown on the bit structure. FIG. 3 is a planview similar to FIG. 2 but shows a bit structure for forming arelatively large hole.

FIG. 4 is a side view of the modification of FIG. 3 and partly brokenaway to show the construction thereof.

DETAILED DESCRIPTION OF THE INVENTION Referring to the drawings somewhatmore in detail, the bit device shown in FIG. 1 comprises an annular bitbody '10 having a central opening or hole 12 extending therethrough andwhich advantageously tapers outwardly as at 14 in a direction toward therear of the bit body.

The bit body is advantageously formed from the rear so that it can beseated on a pipe 16 and welded thereto as by welding 18. Pipe 16 may befurnished with the bit, or it may comprise a length of drill pipe and isthreaded at the end opposite bit body 10 by threads 20 for connectionthereof to another length of drill pipe.

Bit body 10, as will best be seen in FIG. 2, has a plurality of supportblocks 22 distributed thereabout, and in each block, there is rotatablymounted a pick type cutter 24. The cutters 24 are of a known type as arethe blocks 22 and are inclined on the bit body at various angles so asto reduce a substantial radial portion of a formation to which the bitis rotatably presented and including that part of the formation lyingradially outside the envelope of the bit body and the drill string. Thebits and blocks have not been shown in FIG. 1 for the sake of claritybut the location and angular disposition thereof will be clear from FIG.2.

A particular feature of the bit according to the present inventionresides in the bar 26 extending diametrally across central opening 12 ofthe bit body and tiltably connected to the bit body at one end 'as bypin 28. Bar 26 in the center thereof includes a pilot cutter element 30and which may consist, for example, of a transversely extending bladeformed of a hard wear resistant material such as cemented tungstencarbide.

When the bit is presented to a formation and rotated and advanced intothe formation, the rotatable cutter bits 24 and the central pilot cutter30 reduce the formation and the resulting debris can be removed from thehole by forcing flushing fluid such as water through the drill stringand bit and withdrawing the debris along the outside of the drillstring.

When a hole is formed to the desired extent by rotating the bit anddrill string while advancing the bit and drill string into theformation, a pipe 32 which it is desired to place in the hole can beintroduced axially through the drill string and, at that time, thecentral transverse bar 26 will tilt upwardly, as shown in dotted outlinein FIG. 1, and permit the pipe to pass through the bit while, moreimportantly, permitting the bit, together with the drill string, to bewithdrawn from the hole leaving pipe 32 in the hole.

It will be understood that, where the bit is resting on the bottom of ahole that has been drilled, it will be necessary to retract it slightlyfrom its fully advanced position to permit bar 26 to tilt upwardly.However, this still permits the pipe 32 to be introduced substantiallyto the bottom of the hole formed while permitting the drill string andbit to be retracted as a unit from the hole, leaving pipe 32 therein.

The bit arrangement shown in FIGS. 3 and 4 comprises an annular member40 forming the bit body and distributed about annular member 40 is aplurality of blocks 42 each having rotatably mounted therein a pick typecutter element 44. The blocks and cutters are shown in particular indeveloped form in FIG. 4 and illustrate that the radial range of thecutters is such as to reduce the formation into which the bit is movedto permit clear passage for the bit body and, therefore, for the drillstring to which the bit body is connected.

In the case of the modification of FIGS. 3 and 4, the transverse barextending across the central opening 46 of the bit, said bar beingindicated at 48, carries not only a central cutter 50, but also has picktype cutters 52 mounted thereon on each side of the central cutter. Inthis manner, the material through which the bit is being moved isreduced completely across the diameter of the bit body and the removedmaterial can readily be withdrawn along the outside of the drill string.

Central bar 48, similar to bar 26 of FIGS. 1 and 2, is pivotallyconnected by a pin 54 to the bit body so that the bar 48 can tiltupwardly from its working position and thereby permit a pipe to beintroduced directly through the bit before the bit and drill string arewithdrawn from the hole.

Thus, in the case of the modifications of FIGS. 3 and 4, a bit canreadily be recovered from the hole which it forms while, at the sametime, permitting the pipe to be introduced into the hole before thedrill string is withdrawn therefrom.

In the case of either of the modifications illustrated, the savings inbit costs are substantial, while no loss in drilling efficiency and noloss of time is encountered in forming a hole and placing a pipetherein.

The bit body of FIGS. 1 and 2 has the axially extending diametrallyopposed notches 60 and 62 to receive the ends of bar 26 while the bitbody of FIGS. 3 and 4 has the notches 64 and 66 for the same purpose.The notches are effective for transmitting torque from the bit body tothe respective bar' while the notch at the free end of the bar alsoprovides an abutment region to bolt the bar in the proper diametralposition during a hole forming operation.

The pick type cutters have been shown mounted in support blocks and heldtherein as by snap rings but it will be evident that the bit bodiescould be formed with holes to receive the cutters and the cutters heldtherein as by captive keepers. US. Pat. No. 3,752,515 shows a captivekeeper arrangement of the nature referred to while US. Pat. No.3,650,565 shows the use of a snap ring as a keeper. Each of the patentsshows cutters of the type illustrated herein.

Modifications may be made within the scope of the appended claims.

What is claimed is:

1. In an excavating tool; an annular bit body having a central openingtherethrough, an end portion extending from one end of said body smallerin diameter than the bit body and adapted for coaxial extension inside atubular member to be fixedly held there for rotation on a central axis,the central opening in said end portion flaring out toward the free endthereof, cutters mounted on and protruding axially from one axial end ofsaid body for reducing a formation into which the tool is advanced whilerotating, a bar element extending transversely on said one end of saidbody, pivot means pivotally connecting one end of said bar element tosaid body and cooperating elements of abutment means on the other end ofsaid bar element and said body, said abutment means supporting said barelement during excavating operations and said pivot means permittingoutward pivotal movement of the bar element to expose said centralopening, and cutter means on said bar element for reducing the formationradially inwardly from said cutters on said one end of said body.

2. An excavating tool according to claim 1 in which said cutters on saidbody comprise pick type cutters rotatable on the respective axes thereofand all tilted on the bit body in the same circumferential direction.

3. An excavating tool according to claim 1 in which said cutter means onsaid bar element includes a spadetype cutter on the center of the barelement.

4. An excavating tool according to claim 1 which includes means on theother side of said bit body for threaded connection thereof to a tubulardrill string.

5. An excavating tool according to claim 1 in which the central openingon said bit body tapers outwardly in the direction toward the other sideof said body.

6. An excavating tool according to claim 1 which includes a tubularmember telescopically fitted over said extending end portion and coaxialtherewith, said tubular member abutting the bit body at the base of saidextending end portion.

7. An excavating tool according to claim 1 in which said bit bodyincludes diametrally opposed axially extending radial notches in whichthe opposite ends of said bar element are disposed and operable fortransmitting torque from the bit body to said bar element.

8. An excavating tool according to claim 1 in which said cutter means onsaid bar element includes cutter elements mounted on the bar elementradially inwardly from the inner limits of said annular body and allthereof tilted on the bar element in the same circumferential direction.

9. An excavating tool according to claim 8 in which said bar element hasa centrally located spade-type cutter thereon and the said cutterelements thereon being disposed on opposite sides of said spade-typecutter.

1. In an excavating tool; an annular bit body having a central openingtherethrough, an end portion extending from one end of said body smallerin diameter than the bit body and adapted for coaxial extension inside atubular member to be fixedly held there for rotation on a central axis,the central opening in said end portion flaring out toward the free endthereof, cutters mounted on and protruding axially from one axial end ofsaid body for reducing a formation into which the tool is advanced whilerotating, a bar element extending transversely on said one end of saidbody, pivot means pivotally connecting one end of said bar element tosaid body and cooperating elements of abutment means on the other end ofsaid bar element and said body, said abutment means supporting said barelement during excavating operations and said pivot means permittingoutward pivotal movement of the bar element to expose said centralopening, and cutter means on said bar element for reducing the formationradially inwardly from said cutters on said one end of said body.
 2. Anexcavating tool according to claim 1 in which said cutters on said bodycomprise pick type cutters rotatable on the respective axes thereof andall tilted on the bit body in the same circumferential direction.
 3. Anexcavating tool according to claim 1 in which said cutter means on saidbar element includes a spade-type cutter on the center of the barelement.
 4. An excavating tool according to claim 1 which includes meanson the other side of said bit body for threaded connection thereof to atubular drill string.
 5. An excavating tool according to claim 1 inwhich the central opening on said bit body tapers outwardly in thedirection toward the other side of said body.
 6. An excavating toolaccording to claim 1 which includes a tubular member telescopicallyfitted over said extending end portion and coaxial therewith, saidtubular member abutting the bit body at the base of said extending endportion.
 7. An excavating tool according to claim 1 in which said bitbody includes diametrally opposed axially extending radial notches inwhich the opposite ends of said bar element are disposed and operablefor transmitting torque from the bit body to said bar element.
 8. Anexcavating tool according to claim 1 in which said cutter means on saidbar element includes cutter elements mounted on the bar element radiallyinwardly from the inner limits of said annular body and all thereoftilted on the bar element in the same circumferential direction.
 9. Anexcavating tool according to claim 8 in which said bar element has acentrally located spade-type cutter thereon and the said cutter elementsthereon being disposed on opposite sides of said spade-type cutter.